Equine Fecal Microbiota: What’s Normal, and What’s the Colitis Link?

A Texas A&M-led study sought to describe “normal” equine microbiomes and compare those results to horses with colitis related to both antibiotic administration and Salmonella infection.
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Equine Fecal Microbiota: What
Photo: Anne M. Eberhardt/The Horse

​Colitis is a serious disease in horses that causes gastrointestinal (GI) upset, diarrhea (sometimes chronic), and even death. As researchers have learned more about the GI microbiome in humans, horses, and other species, they’ve discovered a relationship between colitis and microbiome imbalance. But does the disease cause imbalance, or does imbalance cause the disease? And what does a “normal” equine fecal microbiome look like? A Texas A&M-led research team investigated by looking at fecal samples in a diverse group of horses. Carolyn Arnold, DVM, Dipl. ACVS, an associate professor at Texas A&M, presented the team’s findings at the 2019 American Association of Equine Practitioners Convention, held Dec. 7-11, in Denver.

A Better Understanding of the Microbiome

Inside the equine gut is a complex community of bacteria, viruses, and fungi that form the GI microbiome. As scientists have learned more about these microbial populations in humans and other animals, they’ve found the health of individuals to be reliant on the “bugs” living inside them.

“As veterinarians we’re all aware we share our lives with bacteria,” said Arnold. “We are, in fact, colonized and outnumbered by them

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Written by:

Michelle Anderson is the former digital managing editor at The Horse. A lifelong horse owner, Anderson competes in dressage and enjoys trail riding. She’s a Washington State University graduate and holds a bachelor’s degree in communications with a minor in business administration and extensive coursework in animal sciences. She has worked in equine publishing since 1998. She currently lives with her husband on a small horse property in Central Oregon.

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